Acacetin attenuates mice endotoxin-induced acute lung injury via augmentation of heme oxygenase-1 activity

Acacetin, a natural product, has a wide spectrum of biological activities such as antioxidant properties. In the present study, we examined whether Acacetin has any beneficial role on lipopolysaccharide (LPS)-induced acute lung injury (ALI) and, if so, whether its effect is mediated via heme oxygenase-1 (HO-1), an antioxidant enzyme playing an important role in ALI. Male BALB/c mice were stimulated with LPS intratracheal instillation to induce ALI. Acacetin was administrated 2 h after LPS challenge. Samples were harvested 10 h after LPS administration. We demonstrated that LPS challenge significantly induced lung histological alterations such as inflammation and edema. Acacetin administration notably attenuated these changes and reduced tumor necrosis factor-alpha and interleukin-1 beta in lung tissues. The LPS-induced reactive oxygen species generation was markedly suppressed by Acacetin. Furthermore, Acacetin treatment significantly elevated pulmonary HO-1 and nuclear factor erythroid-2-related factor 2 (Nrf2) activities. However, the beneficial action of Acacetin was markedly abolished when pretreated with zinc protoporphyrin, an inhibitor of HO-1. In in vitro studies, Acacetin notably increased the HO-1 expression in pulmonary microvascular endothelial cells. During knockdown of Nrf2 by siRNA, the effect of Acacetin on HO-1 expression was significantly reversed. Acacetin attenuates LPS-induced ALI in mice. This protective effect of Acacetin may be mediated, in part, through an HO-1-dependent pathway.